Bentonite greases



Patentecl May 4, 1954 UNITED STATES ATENT OFFICE BEN TON ITE GREASES poration of Delaware No Drawing. Application February 21, 1950, Serial No. 145,595

9 Claims. 1

This invention relates to new and improved lubricating compositions. Particularly the invention relates to lubricatin compositions which comprise an oil thickened to a greaseconsistency with an organophilic bentonite. More particularly the invention relates'to a grease composition having desirable high temperature properties and excellent structural stability which is formed by dispersing into a lubricating base a complex reaction product of a bentonitic type clay and an aliphatic amine salt, utilizing in the dispersing step a solvent exchange procedure.

The complex products formed by reacting bentonite type clays with aliphatic amine salts to produce hydrophobic materials are known in the art. Some of these compounds are described in U. S. Patent 2,033,856, issued to Smith on March 10, 1936. The swelling or" these complexes in organic liquids and liquid mixtures has been observed and a mechanism advanced to account for the solvation phenomenon in an article by John W. Jordan in the Journaloi Physical .Colloid Chemistry, volume 53, No. 2, February, 1949, on pages 294-305, inclusive.

It is also known that certain organophilic bentonites (those where the clay platelets are entirely coated with organic material, known commercially as Bentone 34) may be incorporated into mineral oil by milling at a high rate of shear, resulting in grease-like materials. A copending application Serial No. 135,036, filed December 24, 1949, for Sparks, Morway, and Young, now Patent No. 2,626,241 issued January 20, 1953, reveals that some of these organophilicbentonites may be dispersed in a synthetic oil also .by a milling process to form a very satisfactory grease composition.

It has now been found, and forms the object of this invention, that the expensive and timeconsuming milling step necessarynin the above mentioned dispersing method may be eliminated and that excellent lubricating compositions may be prepared by dispersing in a: lubricating oil, either naturally occurring or synthetic, an organophilic bentonitic type clay using a solvent exchange method.

Briefly stated, the invention comprises a new and useful lubricating composition prepared by spreading the lattice structure of the organophilic bentonite by treating it with a polar material to form a slurry. Thedesired lubricating oil is then worked gradually into the slurry until a suspension is obtained containing all of the required oil. The batch is then heated, the polar material distilled ofi, leaving: the bentonite-oil system as a heavy grease.

f the organophilicbentonitic materials operable in this invention, it is preferred to use the complexes formed by reacting a bentonitic type clay with an aliphatic amine salt in which the aliphatic portion of the amine is a carbon chain of from 10 to 18 carbon atoms. Either the primary aliphatic amine salt or the quaternary amine salt may be used. In the case of the latter salt, the aliphatic portion may be either alike or different, the total number of carbon atoms, however, being preferably within the range of from 10-35.

Normally these complexes are prepared by first reacting the desired aliphatic amine, with an acid, such as acetic or hydrochloric, to form the amine salt, and then adding the amine salt to a water dispersion of the bentonitic material. The complex formed is then washed free of salt, dried, and ground.

The method of this invention is especially adaptable to the primary amine complexes since in these complexes, it is postulated, the lattice structure of the bentonite is not completely coated with polar material and the oil used will not penetrate into the system. This theory explains the lack of success in attempts to form a grease structure with a primary amine complex using the milling procedure. By the use of the polar material, the lattice structure is completely coated and the oil enters the system easily, the polar material may then be distilled off, leaving the desired bentonite lattice-oil system in the form of a solid grease.

Although any of the polar materials having the capacity of increasing the gel volume of the bentonite whichare listed on page 299 of the Jordan article referred to above may be used in the process of this invention, it is preferred to use those materials having lower boiling points. Examples of the preferred lower boiling materials are isopropyl alcohol acetone, ethyl ether, toluene, xylene, and the like. Mixtures of two or more of the polar materials may also be used.

The amount of the polar material used is not critical, it being essential only that the bentonite complex is completely wetted by the liquid used. Ordinarily equal parts of the bentonite complex and the polar material are operable.

The amount of the organophilic bentonite and the lubricating oil used for the formulation of the greases of this invention are not critical so long as the desired. stable grease structure is obtained. For most purposes, however, a grease formed by using from 5% to 50% of the filler has satisfactory structural stability.

The lubricating oil used. to prepare the greases of this invention may be either a naturally occurring oil or a synthetic oil, depending to a certain extent, upon the characteristics desired in the final grease composition. Among the various synthetic oils operable, special mention should be made of the silicone fluids which are excellent lubricants for temperatures in excess of 300 F. Greases made following the concept of this invention utilizing the silicone fluids have dropping points high enough to take advantage of the superior high temperature properties of the silicone fluids.

The concept of this invention may be more completely explained by reference to the following examples:

EXANIPLE I 15 parts by weight of a complex formed from a bentonitic type clay and a primary aliphatic amine salt (octadecyl amine hydrochloride) was mixed with an equal amount of 91% isopropyl alcohol (a small amount of additional alcohol may be added if it appears necessary to com" pletely wet the complex). Into this mixture was added 85 parts of 2. Coastal distillate having a viscosity at 210 F. of U. S. The mixture was slowly worked to break up all lumps and until a smooth slurry was obtained. When the oil was all worked into the mixture the batch was heated at a temperature of EGO-210 F. for three hours to drive oil the solvent. The temperature necessaryto strip the product depends on the volatility of the solvent used. The heat was then removed and the material stirred until it cooled to room temperature.

EXAMPLE II Following the procedure outlined in Example I above, a second grease was prepared in which acetone was substituted for the isopropyl alcohol of Example I.

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EXAMPLE III Using ethyl ether instead of the isopropyl alcohol of Example I, a third grease composition was prepared.

EXAMPLE IV A fourth grease composition was prepared fol-- lowing the procedure of Example I using the following formulation:

Per cent Primary aliphatic amin salt-bentonite complex l5 Carnauba wax 2 Coastal distillate having a viscosity at 210 F. of 50 S. U. S.

The Carnauba wax was added to the mixture of the isopropyl alcohol and bentonite along with the distillate.

EXAMPLE V EXAMPLE VI A second grease composition using the quaternary amine salt-bentonite complex was formed,

using the procedure of Example V but using as the polar material acetone instead of the ethyl ether.

EXAMPLE VII About 15 parts by weight of a primary aliphatic amine salt-bentonite complex was slurried directly with parts by weight of a Coastal distillate having a viscosity at 210 F. of 50 U. S. The slurry was then passed through a colloid mill 5 times. A semi-fluid product resulted which was entirely unsuitable as a lubricating grease composition.

EXAMPLE VIII About 15 parts by weight of a complex formed by reacting a quaternary amine salt with bentonite was admixed with 85 parts by weight 01 the same distillate used in Example VII above. After milling the slurry by two passes through a colloid mill at .602" clearance a solid grease composition resulted.

The greases formed according to the procedures above were submitted to the standard micro penetration worker tests described by G. M. Hain in U. S. Patent 2,477,598. The results of these tests are set forth in Table I below:

Table I.--Bentonite complex greases shear Examination of the data reported in Table 1, above, points out the fact that very desirable structural stability is obtained when the bentonitic greases are made in accordance with this invention. It is also shown that greases made with the quaternary ammonium salt-bentonite complex by this novel procedure are greatly superior in structure stability to the reases made using the expensive and time-consuming milling procedure, the new greases having micropenetrations ranging from 53 to 71, as compared to 203 to 310 for the milled grease. It is also evident that while the milling procedur is quite unsatisfactory for producing a grease with the primary aliphatic amine salt-bentonite complex, excellent greases are obtained with this more convenient solvent-oil exchange method.

As was mentioned above, very desirable high temperature greases may be made following the concept of this invention using various synthetic oils. Particularly desirable for making high temperature greases are the silicone fluids which have excellent lubricating properties at temperatures in excess of 300 F. The following examples set out in detail the preparation of greases utilizing the silicone fluids:

EXAMPLE IX About 15 parts by weight of a primary aliphatic amine salt-bentonitic complex was mixed with sufhcient acetone to make a soft paste, 85% of a aev'zeer Table -II.Bentovie comple.rsilicone fluid Micropenetration (grin/) lljl'asslelis ru 60 es Grease Screen IX complex) -e 510 195 208 212 X complex) 512 152 145 132 An examination of the inspection data in Table I above will show that greases prepared using the silicone oils as dispersants have excellent dropping points and structural stability.

To more specifically point out the characteristics of the greases of this invention, a series of standard inspection tests were run on a grease formed from the primary aliphatic amine saltbentonite complex prepared according to this invention and a grease prepared from the quaternary aliphatic amine salt-bentonite complex prepared by the milling procedure. Both complexes were dispersed in 85% of a Coastal distillate having a viscosity at 210 F. or" 50 S. U. S. and isopropyl alcohol was used as the polar material in preparing the grease of invention. The results of these tests are set out in Table III below:

Table I II .Bentom'tic complex greases [15% complex85% Coastal distillate 50 S. U. S./210 F.]

Primary Quater: Aliphatic gg Complex A ine E Salt Salt Complex Complex Milling ESOlgent (lgrocedure I xc ange wo passes Method of Manufacture (IS0pro through panol) colloid mill) Structural Stability:

Penetrations; (mm/10) original, un-

worked 288 222 1,000 strokes (fine hole worker) 288 220 00,000 strokes (fine hole worker) ii 294 237 Acidity, residual: ASTM Neut. No. (percent as oleic acid) 3.19 0. 6 Dropping Point: F.) 500+ 500+ Wheel Bearing Test: (AXS-l574) Pass Pass Water Adsorption: Percent 120 Boiling Water Emulsion None None Oil separation (50 hrs. at 160 F.) percent; 0 Norma-Hofiman Test (hrs. to 5 p. s. i.

drop-with 0.5% phenyl'alpha-naphthylamine) 456 108 300 F. Stability Test (Micropenetration,

nun/l0):

After 24 hours 83 93 After 120 hours 62 76 After 265 hours 69 67 These data show that the grease of invention is softer in penetration,-but otherwise-equivalent to the grease prepared from the more expensive quaternary amine-bentonite by the milling technique.

The grease compositions of the invention are compatible with the conventional additive materials such as tackiness agents, viscosity index improvers, anti-corrosion agents, oxidation inhibitors, extreme pressure agents, and the like.

To summarize, the instant invention comprises the manufacture of a new and useful lubricating composition wherein the dispersant or thickening agent is a complex reaction product of an aliphatic amine salt and a bentonitic type material and the dispersing agent is'a lubricating oil. The complex is first mixed with a polar material which serves to prepare the complex for mixing with the oil. When the mixture is completed, the oil is stirred in and the resulting mixture is heated to drive off the polar material, leaving a stable complex-oil system. The invention is particularly adapted to forming desirable lubricating compositions with the primary aliphatic amine salt complexes.

What is claimed is:

1. A process for the manufacture of a new and useful lubricating grease composition consisting essentially of reacting a bentonitic clay with a material selected from the class consisting of high molecular weight primary and quaternary aliphatic amine salts of low molecular weight acids to form a complex reaction product, treating said complex reaction product with a substantially equal volume of a polar material of the class consisting of acetone, ethyl ether, isopropyl alcohol, toluene, xylene, and mixtures thereof, dispersing said treated reaction product in a lubricating oil of the class consisting of mineral oils and silicone fluids by a mixing step, and heating said mixture to a temperature above the boiling point of the polar material.

2. A process according to claim 1 wherein said polar material is acetone.

3. A process according to claim 1 wherein said polar material is ethyl ether.

4. A process according to claim 1 wherein said polar material is isopropyl alcohol.

5. A process according to claim 1 wherein the bentonitic clay is reacted. with a primary aliphatic amine salt.

6. A process according to claim 1 wherein the bentonitic clay is reacted with a quaternary aliphatic amine salt.

7. A process according to claim 1 wherein the bentonitic clay is reacted with octadecyl amine hydrochloride.

8. A process for the manufacture of a new and useful lubricating grease composition consisting essentially of reacting a bentonitic clay with a material selected from the class consisting of high molecular weight primary and quaternary aliphatic amine salts of low molecular weight acids to form a complex reaction product, treating from 5% to 50% of said complex reaction prod uct with a substantially equal volume of a material selected from the class consisting of acetone, ethyl ether, and isopropyl alcohol toluene, xylene and mixtures thereof, dispersing said treated reaction product in 50% to of a lubricating oil of the class consisting of mineral oils and silicone fluids by a mixing step, and heating said mixture to a temperature above the boiling point of the polar material to drive off said polar material leaving the complex-oil system as a heavy grease,

9. A process for the manufacture of a new and useful lubricating grease composition consisting essentially of treating a complex reaction product of a bentonitic clay with a material selected from the class consisting of high molecular weight primary and quaternary aliphatic amine salts of low molecular weight acids with a substantially equal volume of a polar material of the class consisting of acetone, ethyl ether, ispropyl alcohol, toluene, xylene, and mixtures thereof, dispersing said treated reaction product in a lubricating oil of the class consisting of mineral oils and silicone fluids by a mixing step, and heating said mixture to a temperature above the boiling point of the polar material.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Jordan, Organophilic Bentonite, Article in Journal of Physical and Colloid Chemistry, vol. 53, No. 2, February 1949 (294-306) pgs. 

1. A PROCESS FOR THE MANUFACTURE OF A NEW AND USEFUL LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF REACTING A BENTONITIC CLAY WITH A MATERIAL SELECTED FROM THE CLASS CONSISTING OF HIGH MOLECULAR WEIGHT PRIMARY AND QUATERNARY ALIPHATIC AMINE SALTS OF LOW MOLECULAR WEIGHT ACIDS TO FORM A COMPLEX REACTION PRODUCT, TREATING SAID COMPLEX REACTION PRODUCT WITH A SUBSTANTIALLY EQUAL VOLUME OF A POLAR MATERIAL OF THE CLASS CONSISTING OF ACETONE ETHYL ETHER, ISOPROPYL ALCOHOL TOLUENE, XYLENE, AND MIXTURES THEREOF, DISPERSING SAID TREATED REACTION PRODUCT IN A LUBRICATING OIL OF THE CLASS CONSISTING OF MINERAL OILS AND SILICONE FLUIDS BY A MIXING STEP. AND HEATING SAID MIXTURE TO A TEMPERATURE ABOVE THE BOILING POINT OF TH POLAR MATERIAL. 